Precious Metal Gold 18K · supply condition
Precious Metal Gold 18K-1/2 Hard
Properties of the 1/2 Hard condition, compared with the other Gold 18K tempers.
Compromise temper for sheet and wire that must still take moderate bending but resist deformation in service.
What is Gold 18K-1/2 Hard?
Gold 18K-1/2 Hard is Gold 18K supplied in the 1/2 Hard condition — compromise temper for sheet and wire that must still take moderate bending but resist deformation in service. Gold 18K-1/2 Hard has a yield strength of 500 MPa (72.5 ksi) and a tensile strength of 640 MPa (92.8 ksi) — stronger than 97% of precious metal grades. Elongation at break is 10% and the elastic modulus is 78 GPa (11.3 Msi). Gold 18K-1/2 Hard has a density of 15.5 g/cm³ (0.56 lb/in³), heavier than 77% of precious metal grades. It melts at 895°C (1,643 °F). O is the default condition FabDigit quotes; 1/2 Hard is available on request or by drawing note.
Advantages
- Easy to machine — 70/100, better than 101% of precious metal grades
- Polishes to a fine finish — 98/100, better than 98% of precious metal grades
- High strength — 500 MPa (72.5 ksi), better than 97% of precious metal grades
- Readily welded — 85/100, better than 93% of precious metal grades
- Good corrosion resistance — 93/100, better than 78% of precious metal grades
Limitations
- Low stiffness — 78 GPa (11.3 Msi), worse than 90% of precious metal grades
- Limited ductility — 10%, worse than 89% of precious metal grades
- Limited formability — 55/100, worse than 88% of precious metal grades
- Heavy — 15.5 g/cm³ (0.56 lb/in³), worse than 77% of precious metal grades
Gold 18K-1/2 Hard properties
Typical room-temperature values for Gold 18K-1/2 Hard — 8 properties are specific to this condition; the rest are grade-level values shared by every Gold 18K temper. Each bar shows where the value sits among the precious metal grades in FabDigit's library — further right is higher.
Physical3
Gold 18K-1/2 Hard has a density of 15.5 g/cm³ (0.56 lb/in³), heavier than 77% of precious metal grades. It melts at 895°C (1,643 °F).
Mechanical12
Gold 18K-1/2 Hard has a yield strength of 500 MPa (72.5 ksi) and a tensile strength of 640 MPa (92.8 ksi) — stronger than 97% of precious metal grades. Elongation at break is 10% and the elastic modulus is 78 GPa (11.3 Msi).
Thermal6
Gold 18K-1/2 Hard is rated for continuous service to 250°C (482 °F). It conducts heat at 190 W/m·K (109.8 BTU/hr·ft·°F), better than 68% of precious metal grades. Thermal expansion is 16 µm/m·K (8.89 µin/in·°F).
Electrical3
Gold 18K-1/2 Hard conducts electricity at 16 % IACS, worse than 61% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (93/100), better than 78% of precious metal grades.
Sustainability4
Producing a kilogram of Gold 18K-1/2 Hard takes about 180,000 MJ of energy and emits 11,000 kg of CO₂ — more than 77% of precious metal grades. Typical recycled content is 30%.
Manufacturability8
Gold 18K-1/2 Hard's machinability is very good (70/100, better than 101% of precious metal grades); weldability excellent (85/100); formability good (55/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other Gold 18K tempers and conditions
Gold 18K is also supplied in 6 other conditions. The full side-by-side table is on the Gold 18K overview.
- ODefaultDefault stocked condition for sheet, wire and tube that will be bent, stamped, drawn or stone-set.200 MPa yield · 140 HB
- Cold WorkedChoose for springy clasps, pins, wire and thin sections needing maximum strength and dent resistance.660 MPa yield · 220 HB
- Stress RelievedUse after cold forming or machining to cut residual stress and stress-corrosion risk while keeping most of the work-hardened strength.580 MPa yield · 205 HB
- 1/2 HardCompromise temper for sheet and wire that must still take moderate bending but resist deformation in service.500 MPa yield · 190 HB
Working with Gold 18K-1/2 Hard
Is Gold 18K easy to machine?
Turns and engraves beautifully with sharp PCD/carbide tools, high speed, low feed and light cuts; annealed material is gummy, so half-hard stock and swarf recovery for refining are standard practice.
Can Gold 18K be welded?
Excellent with pulsed Nd:YAG/fibre laser and PUK micro-TIG using matching 18K filler; oxyacetylene brazing with graded gold solders is routine, but avoid overheating Zn-bearing casting alloys.
Can Gold 18K be formed, bent or molded?
In the annealed temper it rolls, draws, spins and stamps readily with interstage anneals at 650–700 °C; investment casting at 950–1050 °C mould temperature is the dominant route, plus SLM for complex parts.
What surface finishes work on Gold 18K?
Polishes to a mirror with tripoli/rouge and can be electroformed, rhodium- or Pd-plated (whites) and PVD coated; no anodising — ultrasonic and steam cleaning are the usual final steps.
Gold 18K chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Au750 ‰ legal fineness minimum; refiners aim 75.2–75.5 % to stay above assay tolerance | 75 – 75.8 | 75 |
| Agyellow 18K; near zero in Ni/Pd whites | 0 – 16 | 12.5 |
| Zndeoxidiser / colour and flow modifier in casting alloys | 0 – 4 | 0.5 |
| Ni18K white (Au-Ni-Cu-Zn) only; restricted by EU nickel-release rules | 0 – 13 | 0 |
| Pdnickel-free 18K white (Au-Pd-Ag-Cu) | 0 – 15 | 0 |
| Co+Ir+Ru+Sigrain refiners / deoxidisers in casting and 3D-printing powders | 0 – 0.3 | 0.05 |
| Cubalance of the 250 ‰ base metal; up to ~25 % in 18K red/rose | ≥ 0 (balance) | — |
Gold 18K-1/2 Hard — frequently asked
What is Gold 18K-1/2 Hard used for?
Gold 18K-1/2 Hard is typically used for fine jewelry rings and bracelets, watch cases and bezels, dental crowns and inlays, decorative electronics trim, engraved medallions and awards and clasps, cufflinks and findings. In short: premium 18K jewelry gold.
What is the yield strength of Gold 18K-1/2 Hard?
Gold 18K-1/2 Hard has a typical yield strength of 500 MPa (72.5 ksi) and a tensile strength of 640 MPa (92.8 ksi) — stronger than 97% of precious metal grades. Strength varies by condition: see the 7 listed tempers.
Is Gold 18K-1/2 Hard easy to machine?
Yes — machinability is rated very good (70/100, better than 101% of precious metal grades). Turns and engraves beautifully with sharp PCD/carbide tools, high speed, low feed and light cuts; annealed material is gummy, so half-hard stock and swarf recovery for refining are standard practice.
Can Gold 18K-1/2 Hard be welded?
Yes — weldability is rated excellent (85/100). Excellent with pulsed Nd:YAG/fibre laser and PUK micro-TIG using matching 18K filler; oxyacetylene brazing with graded gold solders is routine, but avoid overheating Zn-bearing casting alloys.
What surface finishes work on Gold 18K-1/2 Hard?
Polishes to a mirror with tripoli/rouge and can be electroformed, rhodium- or Pd-plated (whites) and PVD coated; no anodising — ultrasonic and steam cleaning are the usual final steps.
Can Gold 18K-1/2 Hard be formed, bent or molded?
In the annealed temper it rolls, draws, spins and stamps readily with interstage anneals at 650–700 °C; investment casting at 950–1050 °C mould temperature is the dominant route, plus SLM for complex parts.
What is the maximum service temperature of Gold 18K-1/2 Hard?
Gold 18K-1/2 Hard is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in Gold 18K-1/2 Hard?
Yes — Gold 18K-1/2 Hard is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- The Metallurgy of Carat Gold Alloys / Gold Bulletin property compilations — World Gold Council / Springer (2004)
- ASM Handbook Vol. 2 — Properties of Nonferrous Alloys (Precious Metals) — ASM International (1990)
- ISO 9202 Jewellery — Fineness of precious metal alloys — ISO (2019)
- 18K gold casting alloys and SLM powder data — Cooksongold / Legor Group / Hoover & Strong (2023)
- CES EduPack precious-metal eco-property records (scaled to 750 ‰) — Ansys Granta (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.